Opportunities for women in the military have ballooned since 2001, building on 1990s-era changes that opened air combat to them and most naval ship assignments.

At war in Afghanistan and Iraq, the Corps and the other services found their contributions indispensable because of manpower shortages. Female service members did not just free a man to fight abroad like pioneering women troops of earlier generations. They fought right beside him. Some 300,000 women deployed to Iraq or Afghanistan, where more than 150 were killed.

The Corps has been on the vanguard in acknowledging the reality on the ground and the utility of women in combat. It attached women Marines to all-male infantry units in Iraq as Lionesses, to frisk local women in a nod to conservative Muslim sensibilities, then expanded the concept in Afghanistan as Female Engagement Teams.

Yet the Corps is the only service with gender-segregated basic training. It has also been most restrictive in job assignments, keeping women out of 32 percent of billets. For example, while all Army intelligence jobs are open to women officers, the Corps until now put ground intelligence off-limits.

The next commandant must decide whether to ask for an exception keeping women out of infantry units, if the service concludes integration would be detrimental to its performance in combat.

“I don’t know what my successor’s recommendation will be, but the end state is not a foregone conclusion, as some have suggested,” Amos said in a letter to Marine generals. Combat readiness remains the focus, but “the talent pool from which we select our finest warfighters will consist of all qualified individuals, regardless of gender.”

Many male Marines remain strongly opposed to allowing women into the infantry — the heart of the Corps. In an anonymous survey of Marines last summer, males were most concerned about false accusations of sexual harassment or assault, followed by possible fraternization and preferential treatment, The Associated Press reported.

About 17 percent of male respondents said they would quit the Corps if women were moved into combat jobs. More than a third of female respondents said they would volunteer for a ground combat assignment.

Few women would likely join the infantry, judging from other countries that opened all military jobs to women, including Canada, which did so in 2000, and New Zealand, in 2001.

“It’s not a glamorous lifestyle. That’s why a lot of young men don’t want to be grunts either,” Yoo said.

Strength

Meanwhile, the Corps has been researching the physical capabilities of women, surveying personnel on attitudes toward employing them in combat and phasing in more gender-neutral performance standards.

The Corps accepted the first two women into its infantry officer course last year. Both failed to pass the grueling 10-week field training regimen at Quantico, Va. One in four men typically wash out, too. Two more women tried last month. They didn’t make it through the first day’s endurance test.

Starting next year, women Marines will have to perform at least three pull-ups, just like men.